Mounting of blades in axial flow compressors, turbines, or the like



'Aug. 6, 1957 F L SPEED 2,801,822

MOUNTING 0F BLADEs' IN AXIAL 110w COMFRESSORS TURBINES, OR THE LIKEOriginaljiled Jan. 15, 1946 Fig. 2

M By

A Horn ey Uite Stats MOUNTING F BLADES IN AXIAL FLOW COM- PRESSORS,TURBINES, OR THE LIKE Frank Leslie Speed, Abingdon, England, assignor toPower Jets (Research and Development) Limited, London, England, aBritish company 2 Claims. (Cl. 253-48) This invention relates to themounting of the blades in the outer bladed structure of axial flowcompressors, turbines and the like and while its application is notnecessarily limited thereto it can be regarded as being concernedprimarily with the mounting of fixed stator blading in axial flowmultistage compressors, turbines, and ducted fans. Where suchcompressors or like machines are required for high performance purposesin aircraft or similar circumstances, lightness is a desirable featureand it is of course also desirable that the blades should be mounted ina mechanically effective manner while being if possible individuallyremovable. It is also desirable that they should be mounted in such away that constructional considerations in relation to the machine as awhole are conveniently dealt with, notably the insertion and supportingof the blade in a casing. Further the blade mounting should preferablybe such as to leave or provide as smooth and uninterrupted a surface aspossible exposed to the fluid flow in the blade passages. The presentinvention, in its different aspects, seeks to provide for these variousrequirements and is intended to have immediate application to amultistage axial flow compressor to form part of a gas turbine powerplant for aircraft propulsion although the invention is of course notlimited to such application.

The present application is a division of application Serial No. 641,316,in the name of Feilden, filed January 15, 1946, now Patent No.2,623,728.

According to this invention there is provided an outer bladed structureof an axial flow compressor turbine or the like, comprising a circularsection hollow blade supporting structure coaxial with the axis ofrotation of the machine having on its radially inner surface at leastone annularly directed groove alfording a non-retentive bladeseating,and a ring of radially inwardly extending blades or groups of bladeshaving at their radially outer ends root platforms seating in saidgroove, of which ring of blades alternate blade platforms only aredirectly attached to the blade supporting structure, and these platformshave with the platforms of intervening blade platforms complementaryinterengagement whereby said intervening platforms are secured in theseating groove of the ring. Preferably the ungrooved surface of theblade supporting structure is arranged to be in axial register with theexposed faces of the root platforms in the grooves so that the generalprofile of the fluid passages between the blades has a smooth continuouscontour.

In one practical form of the invention, the blade platforms are of Tshape in peripheral cross section, alternate platforms being invertedwith respect to those adjacent to interlock thereunder, and the latteralone being directly attached to the supporting structure. Preferably insuch a case those platforms which are secured directly to the supportingstructure are so secured by the provision of radially outwardlyextending shanks thereon passing through the supporting structure andlocked at an outer part thereof, while the tails of those Tplatformswhich are secured directly to the supporting structure have a clearancefrom the floor of groove to ensure that when so secured they will clampthe cross members of the intermediate, inverted T-platforrns, inposition against the floor of the groove.

Further and more detailed features of the invention will appear from thefollowing description with reference to the example of constructionillustrated in the accompanying drawings, in which:

Figure 1 is a part longitudinal section of a complete axial flowcompressor having a stator construction in accordance with theinvention; and Figure 2 is a fragmentary peripheral transverse sectionof the compressor illustrated in Figure 1; and Figures 3 and 4 arefragmentary axial sections of the compressor taken on the lines III--IIIand IV-IV respectively in Figure 2.

In the construction illustrated, the compressor comprises a multistagebladed rotor 1 operating in an outer casing 2 consituting the mainsupporting structure for a number of rows of stator blades 3. The latterare provided with integral shallow root platforms 4 suitably curved inthe peripheral sense to suit the diameter at which they are placed,these platforms being seated in shallow grooves 5 formed in the innerface of the casing 2.

It will be noted that the blade platforms are made to correspond indepth with the shallow grooves so that the inner exposed surfaces of theplatform and the ungrooved surface portions of the rings are in axialalignment to afford a general profile for the fluid passages between theblades having a smooth continuous contour.

As will be seen from Figures 24 only circumferentially alternate bladesare directly secured in the platform receiving grooves. Each bladeplatform is of T-shape in transverse section taken on a plane normal tothe axis of the casing 2, the tails 4c of alternate: platforms 4aextending into the groove 5 in which they are seated and having integraltherewith the shanks 15 of securing bolts which pass through holesformed in the casing 2 and are held by nuts 16. The intermediateT-shaped platforms dd are inverted with respect to the groove and theirtails 4 are directed radially outwardly and their crossmembers or heads42, which lie on the floor 5a of the groove 5, engage under thecrossmembers or heads 41) of the bolted platforms 4m It is arranged thatthe tails 4c of the latter have a clearance from the floor of the grooveto ensure that the crossmembers or heads 4e of the platforms 4d will beclamped in position in engagement with the floor 5a of the groove by thecrossmernbers or heads 4b of the platforms 4a, this being the only meansprovided of anchoring the former in the groove.

In order to facilitate assembly of the parts, the casing 2 is made intwo halves 2a, 2b flanged at 20, 2d for bolting together as indicated inFigure 2 it being arranged that the last blades 3a in each half areblades which are bolted directly to the casing.

I claim:

1. In an axial flow bladed rotary device, an outer bladed structurecomprising a hollow tubular casing of circular cross-section, saidcasing being formed with a circumferentially extending groove in itsradially inner surface; a circumferentially extending row of radiallyinwardly extending blades within said casing, each blade having at itsradially outer end an individual root platform located in said groove;means securing circumferentially alternate platforms to said casing; andmeans retaining the intermediate platforms located between saidalternate platforms against radially inward displacement, said meanscomprising complementary inter-engaging portions formed on saidalternate and intermediate platforms, the portions on said alternateplatforms overlapping in a radial sense and lying radially within theportions on the intermediate platforms.

2. In an axial flow bladed rotary device, an outer bladed structurecomprising a hollow tubular casing of circular cross-section, saidcasing being formed with a circumferentially extending'groove in itsradiallyinner surface; a circumferentially extending row of radiallyinwardly extending blades within said casing, each blade having at itsradially outer end an individual root platform located in said groove;each platform being T-shaped in transverse cross section taken on aplane normal to the axisof the casing, and having a head extendingcircumferentially of the groove and a tail extending radially;circumferentially alternate platforms having the tails of the T directedradially outwardly, andeach intermediate platform located between theadjacent platforms having the tail of the T directed radially inwardlyand the head of 15 the T seating on the floor of the groove andoverlapping and engaging in a radial sense and lying radially outwardlyof the heads of the Ts of the alternate platforms on each side thereof;and means securing said alternate blades to 5 the casing.

References Cited in the file of this patent UNITED STATES PATENTS747,857 Curtis Dec. 22, 1903 775,108 Elliott Nov. 15, 1904 779,911Curtis Jan. 10, 1905 890,635 FOX June 16, 1908 2,316,813 Schaper Apr.20, 1943 2,510,606 Price June 6, 1950

